移动电磁载荷作用下曲面轨道/电枢动力特性

Dynamic Characteristics of Armature and Rail with Cambered Surface Under Moving Electromagnetic Load

为进一步提高电磁轨道发射器性能，应用LS-DYNA建立电磁轨道发射有限元模型，研究了在C形电枢电磁轨道发射过程中电枢与轨道的接触问题。设计了3种曲率半径的内凹C形电枢与同一曲率半径的轨道，研究了各组合的动态力学响应。数值模拟结果显示：3种曲率半径的内凹C形电枢与轨道的接触力在0～0．1ms期间快速上升；从0．1ms到大约0．74ms期间，接触力一直在振荡，且幅度趋于变小；在0．74ms的时候，电枢达到临界速度，接触力发生较大的振荡；0．755ms时均发生了明显的波动，到达局部极小值。3种电枢接触面压力分布大致相同；轨道挠度曲线非常相似，且在电枢运动过后等值线图几乎没区别。以接触压力的突然大幅波动为标志电枢达到临界速度，且此后电枢与轨道的接触变得不稳定。内凹型曲面电枢与轨道的曲率配合情况对电枢与轨道的动态结构响应影响不大。

In order to further improve the performance of rail electromagnetic launchers （railguns）, we studied the contact between rail and armature during launch processes by a finite element model of railgun established with LS-DYNA code. We designed three C-shaped armatures, which have concave surface trailing edges of different curvature radius, to match rails with curvatures, and calculated the dynamic mechanical response of these armature/rail pairs. The simulation results show that the contact force, for all the three armatures, quickly increases during 0-0.1 ms, fluctuates with relatively small amplitude during from 0.1 ms to approximately 0.74 ms, starts to fluctuate with larger amplitude at about 0.74 ms when the armaan＇e reaches its critical velocity, and eventually changes obviously and reaches a local minimum value at 0.755 ms. Meanwhile, the three armatures have pressure distribution similar to their contact surfaces. As for the rails in the three matches, their deflection curves are similar, and the contour maps of the rail deflection passed by armatures are hardly different. It is concluded that the sharp downward fluctuation of armature/rail contact force marks an armature reaching its critical velocity, and the distribution of contact pressure becomes unsteady afterwards. Additionally, different matches between rail and armature interface show little impact on the dynamic mechanical response of both armature and rail.